Iris recognition is one of the most accurate and widely popular methods in biometric authentication. It is a contactless method that uses digital images of the detail-rich iris texture to create a genuine discrete biometric signature for the authentication. The images may be acquired by near infrared (NIR) light illumination of human eyes. Conventional handheld devices such as smartphone devices have built-in sensors and/or illuminators that are not designed for iris biometric acquisition. The small size of such devices, particularly the thinness characteristic of handheld devices like smartphones, can place constraints on critical optical components utilized for imaging.